The present invention relates generally to visually inspecting surfaces, such as images of such surfaces acquired by a television camera, and more particularly to the suppression of directionally specific patterns on the acquired images in order to expose and better assess other surface features of interest. The features of interest may be flaws or defects on the surface of a moving or stationary workpiece, while the directionally repetitive pattern may be one created by machine marks of a tool that has prepared (machined) the surface in some manner.
Much technology exists and many patents have issued on techniques for inspecting moving and stationary surfaces, but none have dealt with the suppression of machine marks on the surface that extend in specific directions and obscure flaws and defects to the extent that detection and analysis of flaws cannot be adequately made. The reasons for this is that the machine marks themselves appear as defects and/or obscure the defects, particularly on an image of the surface containing defects as provided by a television camera and a cathode ray tube (television) monitor.